JP2017510683A - Composite material - Google Patents

Abstract

A prepreg comprising a fiber reinforcement and a curable resin, the curable resin being based on the total weight of 25 to 35 wt% tetrafunctional epoxy resin and curable resin based on the total weight of the curable resin 18 to 28 wt% bifunctional epoxy resin, 4 to 18 wt% polyethersulfone based on the total weight of the curable resin, 2 to 10 wt% polyamide 12 particles based on the total weight of the curable resin 2 to 10 wt% polyamide 11 particles based on the total weight of the curable resin, 1 to 8 wt% potato-shaped graphite particles based on the total weight of the curable resin, and the total weight of the curable resin 17.4 to 27.4% by weight of a prepreg containing a curing agent for the curable resin.

Description

  The present invention relates generally to pre-impregnated composite materials (prepregs) for use in making high performance composite parts. More specifically, the present invention provides a prepreg that can be cured / molded to form a composite part with high compressive strength and good mechanical properties with high damage tolerance and interlaminar fracture toughness. Objective.

Composite materials are typically composed of a resin matrix and reinforcing fibers as two major components. Composite materials are often required to perform in environments with high demand levels, such as in the aerospace industry, where the physical limits and properties of composite parts are very important.
Pre-impregnated composite materials (prepregs) are widely used in the manufacture of composite parts. A prepreg is a combined body that typically includes an uncured resin and a fiber reinforcement, and is in a form that is easy to mold and cure into a final composite part. By pre-impregnating the fiber reinforcement with resin, the manufacturer can carefully control the amount and location of the resin impregnated into the fiber network and ensure that the resin is distributed throughout the network as desired. Can do. It is well known that the relative amount of fiber and resin in a composite part and the distribution of resin in the fiber network affect the structural properties of the part. Pre-preg is a preferred material for use in manufacturing load bearing or primary structural parts and in particular primary structural parts for aerospace vehicles such as wings, fuselage, bulkheads and steering surfaces. It is important that these parts have sufficient strength, damage tolerance and other requirements that are routinely established for such parts.

Usually, the fiber reinforcement used in prepregs for aerospace aircraft is a multidirectional woven fabric or unidirectional tape containing fibers extending parallel to each other. The fibers are typically in the form of bundles of a number of individual fibers or filaments, which are referred to as “tows”. The fibers or tows can be chopped and randomly oriented in the resin to form a nonwoven mat. These various fiber reinforcement structures are combined with carefully controlled amounts of uncured resin. The resulting prepreg is typically placed between multiple protective layers and wound up for storage or transportation to a manufacturing facility.
The prepreg can also be in the form of short segments of randomly oriented and shredded unidirectional tape to form a nonwoven mat of shredded unidirectional tape. This type of prepreg is referred to as a “quasi-isotropic chopped” prepreg. Quasi-isotropic shredded prepregs are more traditional, except that short length shredded unidirectional tapes (chips) are randomly oriented in the mat rather than shredded fibers Similar to nonwoven fiber mat prepreg.
The compressive strength of the cured composite material is largely determined by the individual properties of the reinforcing fibers and the matrix resin and the interaction between these two types of components. In addition, the fiber-resin volume ratio is an important factor. The compressive strength of a composite part is typically measured at room temperature under dry conditions. However, compressive strength is also typically measured at elevated temperature (180 ° F.) under wet conditions. Many parts have significantly reduced compressive strength under such high temperature and wet conditions.

For many aerospace applications, it is desirable for composite parts to exhibit high compressive strength under both room temperature / dry conditions and high temperature / wet conditions. However, attempts to keep the compressive strength constant under higher temperature / wet conditions often result in adverse effects on other desired properties such as damage tolerance and interlaminar fracture toughness.
Selecting a resin with a higher modulus can be an effective way to increase the compressive strength of the composite. However, the selection of such resins tends to reduce damage tolerance, which is typically measured by a decrease in compression properties, such as compression after impact (CAI) strength. Therefore, it is very difficult to simultaneously increase both compressive strength and damage tolerance including fracture toughness.
Multiple layers of prepregs are typically used to form composite parts having a laminated structure. Such delamination of composite parts is an important failure mode. Delamination occurs when two layers are detached from each other. Important design limiting factors include both the energy required to initiate delamination and the energy required to propagate it. The onset and growth of delamination is often determined by examining Mode I and Mode II fracture toughness. Fracture toughness is usually measured using a composite material having a unidirectional fiber orientation. The interlaminar fracture toughness of the composite is quantified using G1c (Double Cantilever Beam) and G2c (End Notch Flex) tests. In mode I, the precrack delamination is dominated by the peel force, and in mode II, the crack propagates by the shear force.

A simple way to increase interlaminar fracture toughness was to increase the ductility of the matrix resin by introducing a thermoplastic sheet as an interleaf between prepreg layers. However, this approach tends to result in hard non-stick materials that are difficult to use. Another approach was to include a toughened resin interlayer between about 20 and 50 microns thick between the fiber layers. The toughening resin includes thermoplastic particles. Polyamide has been used as such thermoplastic particles.
Current prepregs are well suited for use with the purpose of supplying strong and damage tolerant composite parts, but still higher levels of compressive strength under high temperature and wet conditions, high damage tolerance There is still a continuing need to provide a prepreg that can be used to make composite parts with (CAI) and high interlaminar fracture toughness (G1c and / or G2c).
According to the present invention there is provided a prepreg, resin matrix, material and method as defined in any one of the appended claims.
The present invention provides a pre-impregnated composite material (prepreg) that can be molded to form a composite part having a high level of strength, damage tolerance, and interlaminar fracture toughness. This is achieved without causing a substantial adverse effect on the physical or chemical properties of the uncured prepreg or cured composite part.

The preliminary composite material of the present invention is composed of reinforcing fibers and a matrix. The matrix includes a resin component composed of one or more bifunctional epoxy resins and a polyfunctional epoxy resin. The matrix further includes a thermoplastic particle component, a thermoplastic toughening agent and a curing agent. As a feature of the present invention, the thermoplastic particle component is composed of thermoplastic particles formed from polyamide 12 (nylon 12 or PA12) and thermoplastic particles formed from polyamide 11 (nylon 11 or PA11). Combined with graphite in shape.
The present invention also includes a method for making a prepreg and a method for forming the prepreg into a wide variety of composite parts. The invention also includes composite parts made using the improved prepreg.
By using a mixture of polyamide 12 thermoplastic particles and polyamide 11 thermoplastic particles as described above, and a matrix resin containing potato-shaped graphite, it has improved mechanical properties (particularly tensile strength and G1c) by molding. It has been found that a prepreg capable of forming a composite part is formed. Furthermore, the inventors have found a high level of strength, damage tolerance and interlaminar fracture toughness compared to conventional systems.

According to a preferred embodiment of the present invention, a resin comprising a combination of one or more of the following components is provided: ie in the range of 8 to 34% by weight of the resin, preferably 10 to 32% by weight of the resin, more preferably Is a base resin component in the form of 14 to 26% by weight of the resin and / or a combination of triglycidylaminophenols; 20 to 28% by weight of the resin, preferably 22 to 26% by weight of the resin, more preferably of the resin A further base resin component in the form of a bis-phenol epoxy of 23 to 26% by weight and / or combinations of the above ranges; 25 to 35% by weight of the resin, preferably 27 to 34% by weight of the resin, more preferably 28 of the resin To 33% by weight and / or a further base resin component in the form of tetra-glycidylamine in a combination of the above ranges; Preferably toughening agent in the form of a polyethersulfone in the form of 12 to 24% by weight of the resin, more preferably 14 to 26% by weight of the resin and / or combinations of the above ranges; 2 to 28% by weight of the resin, preferably the resin A resin comprising one or more combinations of curing agents in the form of methyl anhydride (NMA) or diaminodiphenyl sulfone in the range of 4 to 32% by weight, more preferably 14 to 26% by weight of the resin and / or combinations of the above ranges. Provided.
The resin can further include a polyamide as described herein in the range of 10 to 15% by weight of the resin.
Preferred exemplary resins are 25 to 35 wt% tetrafunctional epoxy resin; 18 to 28 wt% difunctional epoxy resin; 4 to 18 wt% polyethersulfone (PES); 2 to 10 wt% Consists of polyamide 12 (PA12) particles; 2 to 10% by weight polyamide 11 (PA11) particles; 1 to 8% by weight potato-shaped graphite (PSG) particles; and 17.4 to 27.4% by weight curing agent Is done. More preferred exemplary resins are 28 to 32 wt% tetrafunctional epoxy resin; 16 to 20 wt% bisphenol A epoxy resin; 3.6 to 7.6 wt% bisphenol F epoxy resin; 7 to 11 wt% 4 to 8 wt% PA12 particles; 4 to 8 wt% PA11 particles; 2 to 8 wt% PSG particles; and 4,4 'as a hardener from 20.4 to 24.4 wt% Consists of DDS.

Preferred exemplary resins are tetrafunctional epoxy resins of 25 to 35% by weight of the resin, preferably 10 to 32% by weight of the resin, more preferably 14 to 26% by weight of the resin and / or combinations of the above ranges; 18 to 28% by weight of the resin, preferably 22 to 26% by weight of the resin, more preferably 23 to 26% by weight of the resin and / or combinations of the above ranges; bifunctional epoxy resin; 4 to 18% by weight of the resin, preferably 5 to 17% by weight of the resin, more preferably 6 to 13% by weight of the resin and / or a combination of the above ranges of polyethersulfone (PES); 2 to 10% by weight of the resin, preferably based on the resin 3 to 9% by weight or 4 to 8% by weight based on resin and / or combinations of the above ranges of polyamide 12 (PA12) particles; based on resin 2 to 10% by weight, preferably 3 to 9% by weight based on resin or 4 to 8% by weight based on resin and / or combinations of the above ranges of polyamide 11 (PA11) particles; 1 to 8% by weight, preferably 2 to 7 wt% or 3 to 6 wt% and / or combinations of the above ranges of potato-shaped graphite (PSG) particles; and 17 to 28 wt% curing agent based on the weight of the resin Preferably from 18 to 27% by weight based on the weight of the resin and / or a combination of these ranges.
Examples of preferred resin formulations are: 30.0% by weight tetrafunctional epoxy resin; 17.9% by weight bisphenol A epoxy resin; 5.7% by weight bisphenol F epoxy resin; 9.0% by weight PES; 6.0 wt% PA12 particles; 6.0 wt% PA12 particles; 3.0 wt% PSG particles; and 22.4 wt% 4,4 'DDS. For this exemplary formulation, MY0721 is a preferred tetrafunctional epoxy resin; Epon825 (DER332-Dow Chemical. Midland, Mich.) Is a preferred bisphenol A epoxy and GY281 (Huntsman Advanced Materials-Brewster, New York) is a preferred bisphenol F epoxy resin, 5003P (Sumitomo Chemical) is a preferred PES, SP10L particles (KOBO Products-South Plainfield, NJ) are preferred PA12 particles, and RilsanPA11 particles (Arkema) , France) are preferred PA11 particles.

In another embodiment, polyamides with a particle size of 5 to 30 microns are preferred for these formulations. Even more preferred are polyamides with a particle size of 10 to 20 microns.
The above as well as many other features and attendant advantages of the present invention will become better understood with reference to the following detailed description.
The pre-impregnated composite material (prepreg) of the present invention is an alternative to current prepregs used to form composite parts in the aerospace industry and any other application where high structural strength and damage tolerance are required. Can be used as a thing. The present invention includes replacing the resin formulation of the present invention in place of the current resin used to make the prepreg. Accordingly, the resin formulation of the present invention is suitable for use in both conventional prepreg manufacturing and curing processes.
The pre-impregnated composite material of the present invention is composed of reinforcing fibers and an uncured resin matrix. The reinforcing fibers may be any of the conventional fiber structures used in the prepreg industry. The matrix resin includes a resin component composed of a bifunctional epoxy resin and / or a polyfunctional aromatic epoxy resin having more than two functionalities. The matrix resin further includes a thermoplastic particle component, a thermoplastic toughening agent, and a curing agent. A feature of the present invention is that the thermoplastic particle component is composed of a mixture of polyamide 12 particles and polyamide 11 particles.

A thermoplastic toughened epoxy resin comprising a mixture of PA12 particles and PA11 particles provides a cured laminate having high interlaminar fracture toughness, especially when combined with potato-shaped graphite particles (PSG) in a resin matrix. However, it was discovered. In a preferred embodiment, the total content of PA11 and PA12 is in the range of 8 to 13% by weight, based on the total weight of the resin, preferably 9 to 12.5% by weight, based on the total weight of the resin, And / or a combination of the above ranges.
In another embodiment, the total content of PA11, PA12 and PSG is in the range of 12 to 18% by weight based on the total weight of the resin, preferably 13 to 16% by weight based on the total weight of the resin And more preferably 14 to 16% by weight based on the total weight of the resin and / or combinations of the above ranges.
The bifunctional epoxy resin used to form the resin component of the matrix may be any suitable bifunctional epoxy resin. It will be understood that this includes any suitable epoxy resin having two epoxy functional groups. The bifunctional epoxy resin may be saturated, unsaturated, cycloaliphatic, alicyclic or heterocyclic. Bifunctional epoxies may be used alone or in combination with polyfunctional epoxy resins to form the resin component. Resin components containing only polyfunctional epoxies are also possible.

Bifunctional epoxy resins include, for example, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A (optionally brominated), glycidyl ether of phenol-aldehyde adduct, glycidyl ether of aliphatic diol, diglycidyl ether , Diethylene glycol diglycidyl ether, Epikote, Epon, aromatic epoxy resin, epoxidized olefin, brominated resin, aromatic glycidyl amine, heterocyclic glycidyl imidine and amide, glycidyl ether, fluorinated epoxy resin , Or any combination thereof. The bifunctional epoxy resin is preferably selected from diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A, diglycidyl dihydroxynaphthalene, or any combination thereof. Most preferred is diglycidyl ether of bisphenol F. Diglycidyl ether of bisphenol F is commercially available under the trade names Araldite GY281 and GY285 from Huntsman Advanced Materials (Brewster, New York) and under the trade name LY9703 from Ciba-Geigy (location). The bifunctional epoxy resin can be used alone or in combination with other difunctional epoxies or multifunctional epoxies to form the resin component.
The resin component can include one or more epoxy resins having more than two functionalities. Preferred polyfunctional epoxy resins are trifunctional or tetrafunctional. The multifunctional epoxy resin can be a combination of trifunctional and multifunctional epoxies. The polyfunctional epoxy resin can be saturated, unsaturated, cycloaliphatic, alicyclic or heterocyclic.
Suitable multifunctional epoxy resins include, for example, phenol and cresol epoxy novolaks, glycidyl ethers of phenol-aldehyde adducts, glycidyl ethers of dialiphatic diols, diglycidyl ethers, diethylene glycol diglycidyl ethers, aromatic epoxies. Resin, dialiphatic triglycidyl ether, aliphatic polyglycidyl ether, epoxidized olefin, brominated resin, aromatic glycidyl amine, heterocyclic glycidyl imidine and amide, glycidyl ether, fluorinated epoxy resin or any combination thereof Includes those based on.

A trifunctional epoxy resin will be understood as having three epoxy groups substituted either directly or indirectly at the para or meta position of the phenyl ring in the backbone of the compound. A tetrafunctional epoxy resin will be understood as having four epoxy groups substituted either directly or indirectly in the meta or para position of the phenyl ring in the backbone of the compound.
The phenyl ring may additionally be substituted with other suitable non-epoxy substituents. Suitable substituents include, for example, hydrogen, hydroxyl, alkyl, alkenyl, alkynyl, alkoxyl, aryl, aryloxyl, aralkyloxyl, aralkyl, halo, nitro, or cyano radical. Suitable non-epoxy substituents can be attached to the phenyl ring in the para or ortho position, or can be attached to a meta position that is not occupied by an epoxy group. Suitable tetrafunctional epoxy resins include N, N, N ′, N′-tetraglycidyl-m-xylenediamine (commercially available under the name Tetrad-X from Mitsubishi Gas Chemical Company, Tokyo, Chiyoda-ku). And Erisys GA-240 (from CVC Chemicals, Morretown, NJ). Suitable trifunctional epoxy resins include, for example, phenol and cresol epoxy novolaks, glycidyl ethers of phenol-aldehyde adducts, aromatic epoxy resins, dialiphatic triglycidyl ethers, aliphatic polyglycidyl ethers, epoxidized olefins, bromines. Bases based on fluorinated resins, aromatic glycidyl amines and glycidyl ethers, heterocyclic glycidyl imidines and amides, glycidyl ethers, fluorinated epoxy resins or any combination thereof.

An exemplary trifunctional epoxy resin is triglycidyl meta-aminophenol. Triglycidyl meta-aminophenol is commercially available from Huntsman Advanced Materials (Monthey, Switzerland) under the trade name Araldite MY0600 and from Sumitomo Chemical Co., Ltd. (Osaka, Japan) under the trade name ELM-120. Another exemplary trifunctional epoxy resin is triglycidyl para-aminophenol. Triglycidyl para-aminophenol is commercially available from Huntsman Advanced Materials (Monthey, Switzerland) under the name Araldite MY0510.
Additional examples of suitable multifunctional epoxy resins include, for example, N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane (Huntsman Advanced Materials (Monthey, TGDDM, Araldite MY720, and MY721). Switzerland) or commercially available from Sumitomo as ELM434.), Triglycidyl ether of paraaminophenol (commercially available from Huntsman Advanced Materials as Arradite MY0500 or MY0510), Tactix556 (commercially available from Huntsman Advanced). ) Dicyclopentadiene-based epoxy resins, tris- (hydroxylphenyl), and Actix742 (commercially available from Huntsman Advanced Materials.) include methanesulfonyl-based epoxy resin or the like. Other suitable multifunctional epoxy resins include DEN438 (from Dow Chemicals (Midland Mich.)), DEN439 (from Dow Chemicals), Araldite ECN1273 (from Huntsman Advanced Materials), and AralditeHN tandMet av. included.
Preferred resin components include difunctional epoxies, trifunctional epoxies and tetrafunctional epoxies. In a preferred resin component, the bifunctional epoxy resin is present in the range of 7% to 27% by weight based on the total weight of the resin matrix. Preferably, the bifunctional epoxy resin is present in the range of 12 wt% to 22 wt% based on the total weight of the resin matrix. More preferably, the bifunctional epoxy resin is present in the range of 15% to 19% by weight based on the total weight of the resin matrix. The trifunctional epoxy resin is present in the range of 15% to 35% by weight based on the total weight of the resin matrix. Preferably, the trifunctional epoxy resin is present in the range of 20% to 30% by weight based on the total weight of the resin matrix. More preferably, the trifunctional epoxy resin is present in the range of 24% to 28% by weight based on the total weight of the resin matrix. The tetrafunctional epoxy resin is present in the range of 5% to 15% by weight based on the total weight of the resin matrix. Preferably, the tetrafunctional epoxy resin is present in the range of 8% to 12% by weight based on the total weight of the resin matrix. More preferably, the tetrafunctional epoxy resin is present in the range of 9% to 11% by weight based on the total weight of the resin matrix. In the preferred resin component, combinations of various preferred ranges of quantities for the three types of epoxy resins are possible.
In accordance with the present invention, the prepreg matrix also includes a thermoplastic particle component consisting of polyamide particles composed of polyamide 12 and polyamide particles composed of polyamide 11.

Polyamide 12 particles are commercially available from a number of sources. Preferred polyamide 12 particles are commercially available from Kobo Products under the trade name SP10L. The SP10L particles contain 98% by weight of PA12. The particle size distribution is 7 to 13 microns and the average particle size is 10 microns. The particle density is 1 g / cm ³ . The PA12 particles are preferably at least 95% by weight PA12 excluding the water content.
Polyamide 11 particles are also commercially available from a number of sources. Preferred polyamide 11 particles are commercially available from Arkema under the trade name Rislan PA11. These particles contain more than 98% by weight of PA11 and have a particle size distribution of 15 to 25 microns. The average particle size is 20 microns. The density of Rislan PA11 particles is 1 g / cm ³ . The PA11 particles are preferably at least 95% by weight PA11 excluding the water content.
Preferably, both PA12 and PA11 polyamide particles should have a particle size of less than 100 microns. The particles are preferably in the size range of 5 to 60 microns, more preferably 5 to 30 microns. The average particle size is preferably 5 to 20 microns. The particles may be regular or irregular in shape. For example, the particles can be substantially spherical or they can be jagged particles. PA11 particles preferably have an average particle size larger than PA12 particles. Preferably, the average particle size of PA12 will be in the range of 5 to 15 microns and the average particle size of PA11 will be in the range of 15 to 25 microns.

The thermoplastic particle component is present in the range of 5% to 20% by weight based on the total weight of the matrix. Preferably, 5 to 15 weights of thermoplastic particles are present. Most preferably, the matrix contains 9 to 13 weight percent thermoplastic particles. The relative amount of PA12 and PA11 particles may vary. The weight of the PA12 particles is preferably equal to or greater than the weight of the PA11 particles. The weight of the PA12 particles is preferably larger than the weight of the PA11 particles. A preferred weight ratio of PA12 particles: PA11 particles is in the range of 1.1: 1.0 to 1.5: 1.0.
The term “potato graphite” is used herein to describe graphite that has been treated to increase the porosity or sphericity of the graphite. This treatment can be performed on natural graphite (eg, scaly graphite) or artificial graphite (eg, highly crystalline synthetic graphite). Prior to treatment, the graphite is typically flaky (eg, plate-like) or flaky graphite having a relatively high degree of crystallinity. The graphite is treated by crushing, rolling, grinding, compression, deformation, etc., and the graphite is bent, folded, shaped, shaped, etc., to make the flakes substantially spherical. This treatment can increase the isotropic graphite over the more anisotropic flake graphite. Potato-shaped graphite may be coated or uncoated. These can be coated by vapor deposition, which typically deposits a highly conductive layer of carbon. PSG particles may exhibit a planar crystal structure, but a CVD carbon layer is deposited thereon as an amorphous carbon coating. Carbon coating can reduce the specific resiliency of PSG. The PSG particles may be coated by other coating processes known in the art, such as metallization or sputtering. They can be coated with any form of carbon or may be coated with a metal or polymer. The term “potato-shaped graphite” is common in the art, as can be seen in the following examples: “High-Purity Graphite Powders for High Performance”, Giovanni Juri, Henri-Albert Wilhelm Jean L'Heureux, Timhnal Ltd. Switzerland, 2007, and “Graphite: High-Tech Supply Sharps Up”, Penny Crossley, industrial Minerals, 2000.

The term “potato-shaped graphite” is usually referred to herein above (any of the naturally occurring products produced by another method or methods produced by such a method). It is also used to describe the graphite having the shape produced by this method. “Potato-shaped graphite” generally ranges from a potato shape to a generally spherical shape. “Potato-shaped graphite” is typically elongated, rectangular, etc., and can include graphite having an elliptical shape, an egg shape, a rectangular shape, an oblate shape, and the like. Both the whole “potato graphite” and the individual particles of “potato graphite” are not necessarily uniform in shape and are not necessarily symmetrical. As used herein, the term “potato-shaped graphite” is intended to encompass graphite produced by the method described above, and graphite having the shape as described in this paragraph.
Typically, PSG has at least one of the following two characteristics: Logan Instrument Corp. When measured according to the method relating to the device sold under the name Model Tap-2, it is between 0.3 and 1.5 g / cc, preferably between 0.5 and 1.4 g / cc, most preferably 1. A tap density between 1.3 g / cc. In addition, the granulometric dispersion was measured according to the method for particle analyzers sold under the name Microtac Model X100 Particle Analyzer, and as a result, the D90 / D10 distribution ratio varied between 2 and 5, and the particle size Between 1 μm and 50 μm, preferably the D90 / D10 distribution ratio varies between 2.2 and 4.2 and the particle size is between 2 μm and 30 μm and / or combinations of the above ranges It is.

We are particularly suitable to increase the conductivity of the prepreg, coated PSG particles supplied by Nippon Power Graphite Company, Japan, having an average particle size of 10 to 20 microns, preferably 15 microns. I found out. Coated PSG typically has a harder surface and lower resistivity than uncoated PSG, and the resistivity can be at least 50% lower than uncoated PSG. In addition, PSG particles from the German NGS Naturegraphit are also suitable for use in the present invention. In addition, other supplier spheroidal or substantially spherical graphite having properties similar to those described above are also suitable for use in the present invention.
Accordingly, the present invention provides a prepreg containing a fiber reinforced curable resin, which contains potato-shaped graphite.
In a further embodiment, the present invention provides a composite comprising a fiber reinforced resin comprising potato-shaped graphite.
In a further embodiment, the present invention provides a resin composition useful for the production of such a prepreg or composite comprising a curable resin containing potato-shaped graphite.

Potato-shaped graphite (PSG) particles are described in US Patent Application Publication No. 2010/0092808, the contents of which are hereby incorporated by reference and have at least one of the following properties: Measured using a Microtac Model X100 particle analyzer with a tap density between 0.3 and 1.5 g / cc, a potato-like shape, and a particle size analysis dispersion such that the D90 / D10 ratio varies between 2 and 5. Particles having a size between 1 and 50 μm. In embodiments where the breaking fibers are also in the resin interlayer, the size and shape of the carbon particles is not as important because both the fibers and the particles contribute to improved conductivity.
Furthermore, the inventors have found that by using broken fibers, the amount of conductive particles required to achieve a given conductivity is less. Potato-shaped graphite is a relatively soft material that partially collapses during resin impregnation, and in addition, due to its shape and softness, when potato-shaped graphite particles are used, the resin composition Reduces the tendency to damage the surface of the rollers used during prepreg manufacture. PSG particles having a spherical or substantially spherical shape are preferable because the conductivity can be improved with the lowest concentration of PSG relative to the resin. The prepreg contains 0.05 to 4.5 wt%, more preferably 0.1 to 3.0 wt%, most preferably between 0.25 wt% and 1.5 wt% potato-shaped graphite. Is preferred.

A suitable potato-shaped graphite (PSG) of one embodiment is a product supplied by NGS Naturegraphit, Germany, called SG25 / 99.95SC with an average particle size of 10 to 30 microns. Alternatively, PSG supplied by Nippon Power Graphite Company, Japan, which has an average particle size of 10 to 30 microns and is called GHDR-15-4, can preferably be used. GHDR-15-4 includes a carbon coating deposited on its outer surface by carbon deposition. Also suitable are spherical or spheroidal graphites available from other providers such as Timrex.
In one embodiment, the composite of the present invention cures two or more separate layers of fiber impregnated resin impregnated with an interleaf layer of resin containing potato-shaped graphite particles between them. Can be formed. These layers preferably comprise unidirectional tows, and the tows of each layer are substantially parallel. The two layers can be joined by compression so that the unidirectional tow is in the same plane. One or more additional fiber layers can also be combined with the tie layer.
The prepreg matrix resin contains at least one curing agent. Suitable curing agents are those that accelerate the curing of the epoxy functional compounds of the present invention, and in particular, those that facilitate the ring-opening polymerization of such epoxy compounds. In particularly preferred embodiments, such curing agents include those compounds that polymerize with the epoxy functional compound (s) in their ring-opening polymerization. Two or more such curing agents can be used in combination.

Suitable curing agents include anhydrides, especially polycarboxylic anhydrides such as nadic anhydride (NA), methyl nadic anhydride (available from MNA-Aldrich), phthalic anhydride, tetrahydrophthalic acid. Anhydride, hexahydrophthalic anhydride (available from HHPA-Anhydrides and Chemicals Inc. (Newwark NJ)), methyltetrahydrophthalic anhydride (available from MTHPA-Anhydrides and Chemicals Inc.) ), Methylhexahydrophthalic anhydride (available from MHHPA-Anhydrides and Chemicals Inc.), endomethylenetetrahydrophthalic anhydride, hexachloroendomethylene-tetrahydro. Phthalic anhydride (available from Chlorendic Anhydride-Velsicol Chemical Corporation, Rosemont, Ill.), Trimellitic anhydride, pyromellitic dianhydride, maleic anhydride (available from MA-Aldrich) ), Succinic anhydride (SA), nonenyl succinic anhydride, dodecenyl succinic anhydride (available from DDSA-Anhydrides and Chemicals Inc.), polysebacic acid polyanhydride, and polyazeline acid polyanhydride Is included.
Further suitable curing agents are aromatic amines such as 1,3-diaminobenzene, 1,4-diaminobenzene, 4,4′-diaminodiphenylmethane, and polyaminosulfones such as 4,4′-diaminodiphenylsulfone ( 4,4′-DDS, available from Huntsman.), 4-aminophenyl sulfone, and 3,3′-diaminodiphenyl sulfone (3,3′-DDS). In addition, suitable curing agents include polyols such as ethylene glycol (EG, available from Aldrich), polypropylene glycol, and polyvinyl alcohol, and phenol-formaldehyde resins such as phenol having an average molecular weight of about 550 to 650. -Formaldehyde resin, pt-butylphenol-formaldehyde resin having an average molecular weight of about 600 to 700, and pn-octylphenol-formaldehyde resin having an average molecular weight of about 1200 to 1400, each of which is HRJ2210 , HRL-2255, and SP-1068 as for Sensitive Chemicals Inc. (Schenectady NY). Also suitable for phenol-formaldehyde resins is a combination of CTU guanamine and a phenol-formaldehyde resin having a molecular weight of 398 (commercially available from Ajinomoto USA Inc. (Teaneck NJ) as CG-125).

Various commercially available compositions can be used as the curing agent of the present invention. One such composition is AH-154, a dicyandiamide type formulation, which is available from Ajinomoto USA Inc. Is available from Other suitable are Ancamide 400 (which is a mixture of polyamide, diethyltriamine and triethylenetetraamine), Ancamide 506 (which is a mixture of amidoamine, imidazoline and tetraethylenepentamine), and Ancamide1284 (This is a mixture of 4,4′-methylenedianiline and 1,3-benzenediamine.) These formulations are available from Pacific Anchor Chemical, Performance Chemical Division, Air Products and Chemicals, Inc. (Allentown, Pa.).
Additional suitable curing agents include imidazole (1,3-diaza-2,4-cyclopentadiene) available from Sigma Aldrich (St. Louis, Mo.), 2-ethyl- available from Sigma Aldrich. 4-methylimidazole and Air Products & Chemicals, Inc. Boron trifluoride amine complexes such as Anchor 1170 available from
Further suitable curing agents include 3,9-bis (3-aminopropyl-2,4,8,10-tetraoxaspiro [5.5] undecane (which is commercially available as ATU from Ajinomoto USA Inc.). And aliphatic dihydrazide (which is also commercially available from Ajinomoto USA Inc. as Ajicure UDH), and mercapto-terminated polysulfide (which is Morton International Inc. (Chicago, Ill.). Commercially available from the state)).
The curing agent (s) is selected so that the matrix cures at an appropriate temperature. The amount of curing agent required to properly cure the matrix will vary depending on a number of factors including the type of resin being cured, the required curing temperature and curing time. Curing agents typically may also include cyanoguanidines, aromatic and aliphatic amines, acid anhydrides, Lewis acids, substituted ureas, imidazoles and hydrazines. The specific amount of curing agent required for each specific situation can be determined by well-established routine experimentation.

Exemplary preferred curing agents include 4,4′-diaminodiphenyl sulfone (4,4′-DDS) and 3,3′-diaminodiphenyl sulfone (3,3′-DDS), both from Huntsman. It is commercially available.
The curing agent is present in an amount ranging from 10% to 30% by weight of the uncured matrix. Preferably, the curing agent is present in an amount ranging from 15% to 25% by weight. More preferably, the curing agent is present in the range of 18% to 24% by weight of the uncured matrix.
3,3′-DDS is a particularly preferred curing agent. This is preferably used as the sole curing agent in an amount ranging from 19% to 23% by weight. Small amounts (less than 2% by weight) of other curing agents, such as 4,4′-DDS, can be included if desired.
The matrix of the present invention also includes a thermoplastic toughening agent. Any suitable thermoplastic polymer can be used as a toughening agent. Typically, the thermoplastic polymer is added to the resin mixture as particles that dissolve in the resin mixture by heating prior to the addition of the curing agent. When the thermoplastic agent is substantially dissolved in the high temperature matrix resin precursor (ie, a blend of epoxy resins), the precursor is cooled and the remaining components (curing agent and insoluble thermoplastic particles) are added.
Exemplary thermoplastic tougheners / particles include any of the following thermoplastic materials, either alone or in combination: polysulfone, polyethersulfone, high performance hydrocarbon polymer, elastomer, and segment This is a modified elastomer.

The toughening agent is present in the range of 5% to 26% by weight, based on the total weight of the uncured resin matrix. The toughening agent is preferably present in the range of 8% to 23% by weight. More preferably, the toughening agent is present in the range of 13% to 18% by weight. A suitable toughening agent is, for example, granular polyethersulfone (PES) sold under the trade name Sumikaexcel 5003P, which is commercially available from Sumitomo Chemicals. Alternatives to 5003P include Solvay polyethersulfone 105RP, or non-hydroxyl terminal grades such as Solvay 1054P. High density PES particles can be used as a toughening agent. The form of PES is not particularly important as PES dissolves during resin formation. High density PES particles can be made according to the teachings of US Pat. No. 4,945,154, the contents of which are hereby incorporated by reference. High density PES particles are also commercially available from Hexcel Corporation (Dublin, Calif.) Under the trade name HRI-1. The average particle size of the toughener should be less than 100 microns to facilitate and ensure complete dissolution of the PES in the matrix.
The matrix contains additional components such as performance enhancers or modifiers and additional thermoplastic polymers as long as they do not adversely affect the prepreg tack and profile or the strength and damage tolerance of the cured composite part. Good. Performance enhancers or modifiers include, for example, flexibility imparting agents, non-particulate toughening agents, accelerators, core shell rubbers, flame retardants, wetting agents, pigments / dyes, UV absorbers, antifungal compounds, fillers, It can be selected from conductive particles and a viscosity modifier.

Suitable accelerators are any of the commonly used urone compounds. Specific examples of accelerators include N, N-dimethyl, N′-3,4-dichlorophenylurea (Diuron), N′-3-chlorophenylurea (Monuron), and preferably N, N- (4- Methyl-m-phenylenebis [N ′, N′-dimethylurea] (eg, Dyhard UR500 available from Degussa) is included and can be used alone or in combination.
Suitable fillers include, for example, either alone or in combination: silica, alumina, titania, glass, calcium carbonate and calcium oxide.
Suitable conductive particles include, for example, either alone or in combination: silver, gold, copper, aluminum, nickel, carbon conductivity grade, buckminsterfullerene, carbon nanotubes and carbon Nanofiber. Metal coating fillers can also be used, such as nickel coated carbon particles and silver coated copper particles.
The matrix may contain a small amount (less than 5% by weight) of an additional non-epoxy thermosetting polymer resin. Once cured, thermosetting resins are not suitable for melting and reshaping. Suitable non-epoxy thermosetting resin materials of the present invention include, but are not limited to, phenol formaldehyde, urea-formaldehyde, 1,3,5-triazine-2,4,6-triamine (melamine), bismaleimide resin The group includes vinyl ester resins, benzoxazine resins, phenol resins, polyesters, cyanate ester resins, epoxide polymers, or any combination thereof. The thermosetting resin is preferably selected from epoxide resins, cyanate ester resins, benzoxazines and phenol resins. Optionally, the matrix further includes a suitable phenolic group-containing resin, such as a resorcinol-based resin, and a resin formed by cationic polymerization, such as a DCPD-phenol copolymer. Further suitable resins are melamine-formaldehyde resins and urea-formaldehyde resins.

The resin matrix is created according to standard prepreg matrix processing. In general, various epoxy resins are mixed together at room temperature to form a resin mixture to which a thermoplastic toughening agent is added. The mixture is then heated to about 120 ° C. for about 1 to 2 hours to dissolve the thermoplastic toughening agent. The mixture is then cooled to about 80 ° C. and the remainder of the components (thermoplastic particle component, curing agent, and other additives (if any)) are mixed into the resin to form the final matrix resin. Formed and impregnated into fiber reinforcement.
The matrix resin is applied to the fiber reinforcement according to any of the known prepreg manufacturing techniques. The fiber reinforcement can be fully or partially impregnated with the matrix resin. In another embodiment, the matrix resin can be applied to the fiber reinforcement as another layer in the vicinity of and in contact with the fiber reinforcement, but is not substantially impregnated in the fiber reinforcement. The prepreg is typically covered on both sides with a protective film and rolled up for storage and transport, typically at a temperature kept well below room temperature to avoid premature curing. If desired, any other prepreg manufacturing process and storage / transport system can be used.

The prepreg fiber reinforcement may be selected from hybrid or mixed fiber systems comprising synthetic or natural fibers or combinations thereof. The fiber reinforcement can preferably be selected from any suitable material such as fiberglass, carbon or aramid (aromatic polyamide) fibers. The fiber reinforcement is preferably carbon fiber. Preferred carbon fibers are in the form of tows containing 3,000 to 15,000 carbon filaments (3K to 15K). Commercial carbon fiber tows containing 6,000 or 12,000 carbon filaments (6K or 12K) are preferred.
The resin formulation of the present invention contains filaments with carbon tow of 10,000 to 14,000, tensile strength of 750 to 860 ksi, tensile modulus of 35 to 45 Msi, and breaking strain of 1.5 to 2. .5%, density is 1.6 to 2.0 g / cm ³ and weight per length is 0.2 to 0.6 g / m, high Glc value (higher than 3.0) This is particularly effective in providing a laminate having 6K and 12K IM7 carbon tows (available from Hexcel Corporation) are preferred. IM7 12K fiber has a tensile strength of 820 ksi, a tensile modulus of 40 Msi, a breaking strain of 1.9%, a density of 1.78 g / cm ³ and a weight per length of 0.45 g. / M. IM7 6K fiber has a tensile strength of 800 ksi, a tensile modulus of 40 Msi, a strain at break of 1.9%, a density of 1.78 g / cm ³ and a weight per length of 0.22 g. / M.
The fiber reinforcement may include cracked (ie, stretch-broken) or selectively discontinuous fibers, or continuous fibers. It is envisioned that the use of cracked or selectively discontinuous fibers can promote composite lay-up and improve formability prior to full cure. The fiber reinforcement may be woven, non-crimped, non-woven, unidirectional, or multiaxial woven structural forms, such as quasi-isotropic shredded prepregs. The woven form can be selected from plain weave, satin or twill style. Non-crimped and multiaxial forms can have many plies and fiber orientations. Such styles and forms are well known in the composite reinforcement field and are commercially available from a number of companies including Hexcel Reinforcements (Villeurbanne, France).

The prepreg may be in the form of a continuous tape, tow prep, web, or chopped length (the chopping and slitting operations can be performed at any time after impregnation). The prepreg can be an adhesive or surface film, and can additionally embed various forms of carriers, both woven, knitted and non-woven. The prepreg may be fully or only partially impregnated, for example, to facilitate air removal during curing.
Exemplary preferred matrix resins include 15% to 19% by weight bisphenol F diglycidyl ether (GY285); 24% to 28% by weight triglycidyl-m-aminophenol (MY0600); 8% to 13%. % By weight of tetrafunctional epoxy (MY721); 13% to 18% by weight of polyethersulfone (5003P) as toughening agent; 4% to 9% by weight of polyamide 12 particles (SP10L); 2% to 7% % By weight of polyamide 11 particles (Rislan PA11) (where the weight ratio of polyamide 12 particles: polyamide 11 particles is 1.2: 1.0 to 1.4: 1.0); and 18 wt. % To 23% by weight of 3,3′-DDS.
The prepreg can be molded using any of the standard techniques used to form composite parts. Typically, one or more layers of prepreg are placed in a suitable mold and cured to form the final composite part. The prepreg of the present invention can be fully or partially cured using any suitable temperature, pressure, and time conditions known in the art. Typically, the prepreg is cured in an autoclave at a temperature between 160 ° C and 190 ° C. The composite material can be cured using a method selected from microwave radiation, electron beam, gamma radiation, or other suitable thermal or non-thermal radiation.

The prepreg of the present invention can be characterized by its resin content and / or its fiber and resin capacity and / or its degree of impregnation as measured by a moisture absorption test.
The resin and fiber content of the uncured prepreg or composite is determined according to ISO 11667 (Method A) for molding materials or structures containing fiber materials that do not contain unidirectional carbon. The resin and fiber content of uncured prepreg or composite containing unidirectional carbon fiber material is determined according to DIN EN 2559A (Code A). The resin and fiber content of the cured composite containing the carbon fiber material is determined according to DIN EN 2564A.
The volume percent of prepreg or composite fiber and resin can be determined by dividing the weight percent of fiber and resin by the respective density of the resin and carbon fiber.
The impregnation rate (%) of the tow or fiber material impregnated with the resin is measured by a moisture absorption test.

The moisture absorption test is performed as follows. Six strips of prepreg are cut to a size of 100 (+/− 2) mm × 100 (+/− 2) mm. Except for all backing sheet materials. The sample is weighed to approximately 0.001 g (W1). The strips are placed between the PTFE backing aluminum plates so that a 15 mm prepreg strip protrudes from one end of the PTFE backing plate assembly, thereby extending the fiber orientation of the prepreg along its protruding portion. Place the clamp on the opposite end and immerse the 5 mm overhang in water at a temperature of 23 ° C. at a relative air humidity of 50% + / − 35% and an ambient temperature of 23 ° C. After soaking for 5 minutes, remove the sample from the water and remove all the outside water with blotting paper. The sample is then weighed again (W2). The water absorption WPU (%) is then calculated by averaging the weights measured for the six samples as follows: WPU (%) = [(<W2> − <W1>) / <W1> ) × 100. WPU (%) indicates the degree of resin impregnation (DRI).
Typically, the resin weight content values for the uncured prepreg of the present invention are 15 to 70% by weight of prepreg, 18 to 68% by weight of prepreg, 20 to 65% by weight of prepreg, 25 to 60% by weight of prepreg. %, 25-55% by weight of prepreg, 25-50% by weight of prepreg, 25-45% by weight of prepreg, 25-40% by weight of prepreg, 25-35% by weight of prepreg, From 25 to 30% by weight, from 30 to 55% by weight of the prepreg, from 32 to 35% by weight of the prepreg, from 35 to 50% by weight of the prepreg, and / or combinations of the above ranges.

Typically, the resin volume content values for the uncured prepreg of the present invention are 15 to 70% by volume of prepreg, 18 to 68% by volume of prepreg, 20 to 65% by volume of prepreg, 25 to 60% by volume of prepreg. %, 25 to 55% by volume of prepreg, 25 to 50% by volume of prepreg, 25 to 45% by volume of prepreg, 25 to 40% by volume of prepreg, 25 to 35% by volume of prepreg, From 25 to 30% by volume, from 30 to 55% by volume of prepreg, from 35 to 50% by volume of prepreg, and / or combinations of the aforementioned ranges.
The moisture absorption values for the uncured prepreg molding material and tow of the present invention are 1 to 90%, 5 to 85%, 10 to 80%, 15 to 75%, 15 to 70%, 15 to 60%. 15 to 50%, 15 to 40%, 15 to 35%, 15 to 30%, 20 to 30%, 25 to 30%, and / or combinations of the above ranges May be. In a further embodiment, the present invention provides a structure in which one layer of unidirectional fiber tow completely impregnated with a liquid resin is overlaid on one layer of dry unimpregnated unidirectional fiber tow. And then consolidating the structure so that the resin penetrates into the spaces between the unimpregnated tows but the spaces between the filaments in the tows remain at least partially unimpregnated. provide. The support fabric or support scrim can be supplied on one or both sides of the structure, preferably prior to consolidation.

In a preferred embodiment, the tow interior is at least partially free of resin and provides a path or structure for exhausting air so that it is introduced during impregnation with air or liquid resin that may be present in the tow from the beginning. The air that can be done is not trapped inside the structure by the resin and can be exhausted during prepreg manufacture and consolidation. If the resin impregnation does not support the resin on the surface of part or all of the second side surface of the fiber layer, the air flows along the length of the tow and from the second side surface of the fiber layer. Can be discharged. In particular, in addition, if one side of the prepreg is not completely covered with resin, air trapped between the prepregs during the formation of the laminate is exhausted by providing space between the tow filaments. obtain.
The prepregs of the present invention can usually be produced from available epoxy resins, which contain a hardener or curing agent and may optionally contain an accelerator. In a preferred embodiment, the epoxy resin does not contain conventional curing agents, such as dicyandiamide, and in particular, we have found that desirable prepregs are anhydrides, especially polycarboxylic acid anhydrides; amines, especially aromatics. Amines such as 1,3-diaminobenzene, 4,4′-diaminodiphenylmethane, in particular sulfones and methylenebisanilines such as 4,4′-diaminodiphenylsulfone (4,4′DDS) and 3,3′-diaminodiphenyl Sulfone (3,3′DDS), 4,4′-methylenebis (2-methyl-6-isopropylaniline) (M-MIPA), 4,4′-methylenebis (3-chloro-2,6-diethyleneaniline) ( M-CDEA), 4,4′-methylenebis (2,6-diethyleneaniline) (M-DEA), and phenol-form Aldehyde resins, and / or it has been found that can be obtained by the use of a curing agent such as a combination of the aforementioned curing agents. Preferred curing agents are methylene bisaniline and aminosulfone, especially 4,4 ′ DDS and 3,3 ′ DDS. The relative amount of curing agent and epoxy resin to be used depends on the reactivity of the resin, the desired shelf life, the desired processing characteristics, and the nature and amount of fiber reinforcement in the prepreg.

In order to produce a composite having substantially constant mechanical properties, it is important to mix structural fibers and epoxy resin to provide a substantially homogeneous prepreg. Preferred prepregs of the present invention contain low levels of voids between tows. Accordingly, it is preferred that the prepreg and prepreg laminate each have a moisture absorption value of less than 6% or less than 2%, more preferably less than 1%, and most preferably less than 0.5%. The moisture absorption test determines the degree of waterproofing or impregnation between the unidirectional tows of the prepreg of the present invention. In this test, a prepreg specimen is first weighed and clamped between two plates in such a way that a 5 mm wide strip projects. The arrangement is suspended in the fiber direction in a water bath at room temperature (21 ° C.) for 5 minutes. The specimen is then removed from the plate and weighed again, and the weight difference gives a value for the degree of impregnation within the specimen. The smaller the moisture absorption, the higher the degree of waterproofing or impregnation.
Composite parts made from the improved prepreg of the present invention find use in creating articles such as aerospace aircraft primary and secondary structures (wings, fuselage, bulkheads, etc.). It would also be useful in many other high performance composite applications, including automotive, railway and marine vessel applications where high compressive strength, interlaminar fracture toughness and impact damage resistance are required.
The following background information and examples of the present invention will now be helpful in order to more readily understand the present invention.

Example 1
Preferred exemplary resin formulations were prepared as shown in Table 1. A matrix resin was prepared by mixing the epoxy component and polyethersulfone at room temperature to form a resin blend and heating it at 120 ° C. for 60 minutes to completely dissolve the polyethersulfone. The mixture was cooled to 80 ° C. and the remainder of the ingredients were added and mixed thoroughly.

A prepreg was prepared by impregnating one or more layers of unidirectional carbon fibers with the resin formulation of Table 1. A prepreg was made using unidirectional carbon fiber (12K IM7 available from Hexcel Corporation), where the matrix resin was 35 weight percent of the total weight of the uncured prepreg, and the fiber basis weight was 1 square meter 145 grams per gsm (gsm). Various prepreg layups were prepared using standard prepreg manufacturing procedures. The prepreg was cured in an autoclave at 177 ° C. for about 2 hours. The cured prepreg was then subjected to standard tests to measure damage tolerance (CAI) and interlaminar fracture toughness (G1c and G2c).

Compression after impact (CAI) was measured using a 270 inch-pound (in-lb) impact against a 32-ply quasi-isotropic laminate. The laminate was cured in an autoclave at 177 ° C. for 2 hours. The final laminate thickness was about 4.5 mm. Consolidation was confirmed by c-scan. Samples were machined, impacted, and tested according to Boeing test method BSS7260 for BMS 8-276. Those values were normalized to a nominal laminate thickness of 0.18 inches.
G1c and G2c are standard tests for measuring the interlaminar fracture toughness of the cured laminate. G1c and G2c were measured as follows. A 26-ply unidirectional laminate with a 3 inch fluoroethylene polymer (FEP) film acting as a crack starter inserted perpendicular to the fiber direction, along one end, at the lay-up mid-plane Cured. The laminate was cured in an autoclave at 177 ° C. for 2 hours to obtain a nominal thickness of 3.8 mm. The pressure density was confirmed by C-scan. Both G1c and G2c samples were machined from the same cured laminate. G1c was tested according to Boeing test method BSS7233 and G2c was tested according to BSS7320. The values for G1c and G2c were not normalized.
The 0 ° compressive strength at room temperature under dry conditions was measured according to BSS7260. The 0 ° compressive strength at 180 ° F. under wet conditions was also measured according to BSS7260.
The CAI of the cured prepreg was 54.7, and G1c and G2c were 3.6 and 10.4, respectively. Both CAI and G2c are well above acceptable limits for structural parts. However, the G1c of 3.6 was very high and unexpected. G1c values greater than or equal to 3.0 are considered to be very high values for interlaminar fracture toughness, which are the values desired in the context of this application along with other mechanical properties including tensile strength. The 0 ° compressive strength at room temperature under dry conditions was 293 and the 0 ° compressive strength at 180 ° F. under wet conditions was 188.

Example 2
Another prepreg was prepared in the same manner as Example 1. The prepreg was the same as Example 1 except that the fiber reinforcement was 12K IM10. IM10 is a unidirectional carbon fiber material and is also available from Hexcel Corporation (Dublin, Calif.). IM10 12K fiber has a tensile strength of 1010 ksi, a tensile modulus of 45 Msi, a fracture strain of 2.0%, a density of 1.79 g / cm ³ and a weight per length of 0.32 g. / M.
The prepreg contained matrix resin in an amount of 35 weight percent of the total weight of the uncured prepreg, and the fiber basis weight of IM10 fibers was 145 grams / square meter (gsm).
32-ply and 26-ply laminates were cured and tested in the same manner as in Example 1. The CAI of the cured prepreg was 54.4, and G1c and G2c were 2.1 and 9.1, respectively. CAI, G1c, and G2c all exceed acceptable limits for structural parts. The prepreg of Example 1 in which the fibers are IM7 carbon fibers is preferred because G1c is much higher. The 0 ° compressive strength at room temperature under dry conditions was 271 and the 0 ° compressive strength at 180 ° F. under wet conditions was 193.

Examples 3 to 5
Three other prepregs were prepared in the same manner as Example 2 except that the amount of PA12 and PA11 particles was varied. The matrix formulation is shown in Table 2. The prepreg contained matrix resin in an amount of 35 weight percent of the total weight of the uncured prepreg, and the fiber basis weight of 12K IM10 fiber was 145 grams per square meter (gsm).

The cured prepreg was subjected to the same test procedure as Example 1. The results are shown in Table 3.

Compressive strength, CAI, G1c, and G2c are all above acceptable limits for structural parts. The amount of PA12 particles and PA11 particles is preferably 5 to 20% by weight of the total resin weight in order to maximize the interlaminar fracture toughness of both G1c and G2c. Furthermore, it is preferable that the weight of the PA12 particles is larger than the weight of the PA11 particles. A preferred ratio is 1.1: 1 to 1.5: 1.

Example 6
A prepreg was prepared and cured in the same manner as Example 1. The matrix formulation contained polyamide particles commercially available from Arkema (France) under the trade names Orgasol 1002 and Orgasol 3803. Orgasol 1002 is composed of 100% PA6 particles with an average particle size of 20 microns. Orgasol 3803 is a copolymer of 80% PA12 and 20% PA6, composed of particles with an average particle size of 17 to 24 microns. A prepreg was prepared using the same IM7 carbon fiber as in Example 1. The prepreg contained 35% by weight resin and had a fiber basis weight of 145 gsm. Table 4 shows the formulation used for the prepreg.

The cured prepreg was tested in the same manner as Example 1. The CAI was 57.9 and G1c and G2c were 2.1 and 7.3, respectively. The 0 ° compressive strength at room temperature under dry conditions was 269, and the 0 ° compressive strength at 180 ° F. under wet conditions was 160. The G1c of the cured comparative prepreg was significantly lower than the G1c value of the cured prepreg of Example 1 made using the epoxy resin according to the present invention, which was 11% by weight based on the total weight of the resin matrix. SP10L polyamide 12 particles and Rislan polyamide particles are included, and the ratio of SP10L particles: Rislan PA11 particles is 1.3: 1.

Examples 7-9
Prepregs (Comparative Example 2 to Comparative Example 4) were prepared in the same manner as Example 2 using 12K IM10 fibers. The formulations for the comparative matrix are shown in Table 5. Rislan PA11 particles are formed of polyamide 11 and are commercially available from Arkema. Rislan PA11 particles had an average particle size of 20 microns.

The cured prepreg was subjected to the same test procedure as Example 1. The results are shown in Table 6.

Example 7 is the same as Example 6 except that the fiber support is 12K IM10 carbon fiber instead of 12K IM7 carbon fiber. Both comparative examples have comparable interlaminar fracture toughness (2.2 and 2.1, respectively). This means that when the thermoplastic particles are all made of PA12, the fiber type has little effect on G1c. Thus, when using the resin matrix according to Examples 1 and 2, it is expected that the interlaminar fracture toughness will increase from 2.1 to 3.6 when similarly changed from 12K IM10 carbon fiber to 12K IM7 carbon fiber. It is an unobtainable result.
Examples 8 and 9 have acceptable interlaminar fracture toughness. However, the CAI value was less than 50. This is much lower than the CAI value obtained using the resin formulation according to the invention.

Example 10
A prepreg was prepared and cured in the same manner as Example 1. The matrix formulation contained PA11 polyamide particles obtained commercially in the form of Rislan 11 from Arkema (France) and PA12 obtained from KOBO under the name SP10L. PSG is SG25 / 99.95. A prepreg was prepared using the same IM7 carbon fiber as in Example 1. The prepreg contained 35% by weight of resin and the fiber basis weight was 145 gsm. The formulations used for prepregs P1 and P2 are listed in Tables 7 and 8, respectively.


The cured prepreg was tested in the same manner as Example 1. G1c of P1 and P2 was 2.9 and 3.2, respectively. The 0 ° tensile strength (normalized) at room temperature under dry conditions was 379 Ksi and 393 Ksi, respectively (the tensile strength of PSG-containing prepreg was increased), while its modulus remained the same.
From the exemplary embodiments of the present invention thus described, those skilled in the art will appreciate that what is within the scope of the disclosure is merely exemplary, and that various other alternatives, adaptations, and modifications are possible within the scope of the present invention. It should be noted that. Accordingly, the present invention is not limited to the above-described embodiments, but is limited only by the following claims.
Thus, the resin matrix which improved the G1c performance with the prepreg and the tensile strength is disclosed.

Claims (20)

A prepreg comprising a fiber reinforcement and a curable resin,
This curable resin
25 to 35% by weight of tetrafunctional epoxy resin, based on the total weight of the curable resin,
18 to 28% by weight of a bifunctional epoxy resin, based on the total weight of the curable resin,
4 to 18% by weight of polyethersulfone, based on the total weight of the curable resin,
2 to 10% by weight polyamide 12 particles, based on the total weight of the curable resin,
2 to 10% by weight polyamide 11 particles, based on the total weight of the curable resin,
1 to 8% by weight of potato-shaped graphite particles based on the total weight of the curable resin, and 17.4 to 27.4% by weight of a curing agent for the curable resin based on the total weight of the curable resin Prepreg.   The prepreg according to claim 1, wherein the bifunctional epoxy resin is a mixture of a bisphenol A epoxy resin and a bisphenol F epoxy resin.   The curable resin is 16 to 20% by weight bisphenol A epoxy resin based on the total weight of the curable resin, and 3.6 to 7.6% by weight bisphenol F epoxy resin based on the total weight of the curable resin. The prepreg according to claim 2 comprising.   The prepreg of claim 1, wherein the amount of polyamide 12 particles is equal to the amount of polyamide 11 particles.   The prepreg according to claim 4, wherein the amount of polyamide 12 particles is 6% by weight, based on the total weight of the curable resin.   The prepreg according to claim 1, wherein the fiber reinforcement includes fibers selected from the group consisting of carbon fibers, glass fibers, and aramid fibers.   The composite material comprising a prepreg according to claim 1, wherein the curable resin is cured to provide a cured prepreg.   The composite material of claim 7, wherein the cured prepreg is a component of an aircraft.   The composite material of claim 8, wherein the aircraft component is a fuselage. A method for producing a prepreg comprising the steps of supplying a fiber reinforcement and applying a curable resin to the fiber reinforcement,
This curable resin
25 to 35% by weight of tetrafunctional epoxy resin, based on the total weight of the curable resin,
18 to 28% by weight of a bifunctional epoxy resin, based on the total weight of the curable resin,
4 to 18% by weight of polyethersulfone, based on the total weight of the curable resin,
2 to 10% by weight polyamide 12 particles, based on the total weight of the curable resin,
2 to 10% by weight polyamide 11 particles, based on the total weight of the curable resin,
1 to 8% by weight of potato-shaped graphite particles based on the total weight of the curable resin, and 17.4 to 27.4% by weight of a curing agent for the curable resin based on the total weight of the curable resin Prepreg manufacturing method.   The method for producing a prepreg according to claim 10, wherein the bifunctional epoxy resin is a mixture of a bisphenol A epoxy resin and a bisphenol F epoxy resin.   The curable resin is 16 to 20% by weight bisphenol A epoxy resin based on the total weight of the curable resin, and 3.6 to 7.6% by weight bisphenol F epoxy resin based on the total weight of the curable resin. The method of manufacturing the prepreg of Claim 11 containing.   The method for producing a prepreg according to claim 1, wherein the amount of polyamide 12 particles is equal to the amount of polyamide 11 particles.   The method for producing a prepreg according to claim 13, wherein the amount of polyamide 12 particles is 6% by weight based on the total weight of the curable resin.   The method for producing a prepreg according to claim 10, wherein the fiber reinforcement includes fibers selected from the group consisting of carbon fibers, glass fibers, and aramid fibers.   A method comprising: after the step of producing the prepreg of claim 10, curing a curable resin to form a composite material.   A method for producing a composite material comprising the steps of providing a prepreg according to claim 1 and curing a curable resin.   The method of manufacturing a composite material according to claim 17, wherein the composite material is a component of an aircraft.   The method of manufacturing a composite material according to claim 18, wherein the aircraft component is a fuselage. A resin matrix,
25 to 35% by weight of tetrafunctional epoxy resin, based on the total weight of the curable resin,
18 to 28% by weight of a bifunctional epoxy resin, based on the total weight of the curable resin,
4 to 18% by weight of polyethersulfone, based on the total weight of the curable resin,
2 to 10% by weight polyamide 12 particles, based on the total weight of the curable resin,
2 to 10% by weight polyamide 11 particles, based on the total weight of the curable resin,
1 to 8% by weight of potato-shaped graphite particles based on the total weight of the curable resin, and 17.4 to 27.4% by weight of a curing agent for the curable resin based on the total weight of the curable resin , Resin matrix.